Solvent extraction process for the recovery of copper values

ABSTRACT

The coalescence rate of an aqueous/liquid hydrocarbon emulsion system is enhanced by the presence of an alkylated phenol as a minor part of the organic phase. Such hydrocarbon solutions further containing a chelation metal collector can be advantageously employed in the liquid ion exchange process for the extractive recovery of metal values from dilute aqueous solutions thereof.

; tates atent [111 Memes Hartlage et a1. 1 51 A1. 3, 1973 [54] SOLVENTEXTRACTTON PROCESS 3,131,998 5/1964 Swanson ..75 101 BE UX FOR THE ECOERY OF COPPER 3,239,565 3/1966 Kreevoy et a1 ..75/101 BE UX VALUES3,428,449 2/1969 Swanson ..75/117 3,449,246 6/1969 Pelka et a1. ..75/l01BE UX [75] Inventors; James Albert Hal-age, m 3,558,288 1/1971 Burrows..23/312 Alvin Dale Cronberg, Bloomington, both of Minn PrzmaryExammer-G. T. Ozak1 Attorney-Walter H. Schneider, William Kammerer, gAshland Oil, -1 Ashland, y- Van D. Harrison, Jr. and Harold M. Dixon[22] Filed. Feb. 22, 1971 [57] ABSTRACT [21] Appl' u7826 The coalescencerate of an aqueous/liquid hydrocarbon emulsion system is enhanced by thepresence of 52 us. (:1. ..7s/101 BE, 75/117, 23/312 R alkylated Phenolas a P 51 Int. Cl. ..C22b 15/08 i S f solutgmscfunher contlamng a c eanon meta co ector can e a vanta' eous em- [58] held 117; 11 5 plo'yedin the liquid ion exchange process for thZ ex- 23/312 tractive recoveryof metal values from dilute aqueous solutions thereof. [56] ReferencesCited 7 Claims, N0 Drawings UNITED STATES PATENTS 3,224,873 12/1965Swanson ..75/101 R SOLVENT EXTRACTION PROCESS FOR THE RECOVERY OF COPPERVALUES BACKGROUND OF THE INVENTION 1. Field of the Invention Thisinvention relates to an improvement in a liquidliquid hydrometallurgicalextraction process for the recovery of metal values from dilute aqueoussolutions thereof.

2. Description of the Prior Art The application of liquid ion exchangeextraction principles to hydrometallurgical operations for the recoveryof metal values from dilute aqueous solutions thereof or thefractionation of a mixture of such values, has of late commanded everincreasing attention from the hydrometallurgy industry. Developments,have, however, progressed in this area to the extent that it is nowcommercially feasible to recover the copper values from leaches of lowgrade sulfide ores in a sufficiently pure and concentratedform so as topermit the electrolytic refinement thereof.

The liquid ion exchange process, in context of extractive metallurgy,basically involves two distinct steps. In the first step, an impureaqueous phase containing the desired metal values in ionic form isintimately contacted with a water-immiscible organic solution of a metalion collector to facilitate an interfacial relationship of the phaseswhereby the metal ions are readily and preferentially extracted into theorganic phase. The second step, referred to as stripping, serves toregenerate the extracted metal values in ionic form and to effect thetransfer thereof to an aqueous phase to provide a pure and relativelyconcentrated solution of the desired metal.

There are two general types of metal ion collectors which have found usein the aforedescribed liquid extraction process; namely, those that forma heteropolar or electrovalent salt with a metal ion and those forminginternal (chelate) complexes therewith. The latter type are favoredbecause of their inherent versatility and demonstrated potential forpurifying and concentrating metal values from solutions economically.From a technical standpoint, the chelation metal collectors are organiccompounds containing, in addition to a replaceable hydrogen atom, afunctional group of basic character, such as NH N-, and 0. Suchcollectors are capable of coordinating with a metal ion through covalentbonding to form a relatively stable fiveor six-membered ring. The mosteffective of this type of collector known presently are those compoundswhich contain either the 8-hydroxy quinoline structure or a hydroxyhydrocarbyl substituted oxime radical in the molecular configurationthereof. Of the latter, those compounds wherein the hydrocarbylsubstituent is aromatic are proposed as being the more efficientcollectors of this class.

Notwithstanding that the hydrometallurgy industry has had made availableto them highly effective chelation collectors, anunassociated problemnevertheless remains in carryingout the extraction process. As indicatedpreviously, the extraction step as well as the stripping step call forintimately mixing an organic phase with an aqueous phase. Technicallythis gives rise to an emulsion system and therefore an ensuing sharp andquick separation of the phases, particularly a fast separation, isessential in order to have a commercially applicable extraction process.Fast separation of the phases is of utmost importance because thecoalescence rate governs the amount of aqueous solu tion which can beextracted per unit of time. Sharp separation is necessary becauseessentially no loss of the costly collector by entrainment in theaqueous raffinate can be economically tolerated. Moreover, the loadedaqueous phase provided by the stripping step must be free of entrainedmaterial so that the efficiency of the subsequent electrolyticrefinement operation is not adversely affected.

Heretofore, it has been known that the presence of a higher alcohol,e.g., isodecanol, in the organic phase during either the extraction orstripping stepenhances the rate of coalescence of the respective phasesin the settling operation. However, the need remains for a surfaceactive agent which will not only provide a faster rate of coalescencebut for one which will result in a cleaner separation of the phases uponcoalescence.

- SUMMARY OF THE INVENTION In accordance with the present invention, analkylated phenol having an alkyl moiety containing from six to 12 carbonatoms is utilized in conjunction with a metal ion collector in anotherwise conventional liquidliquid ion exchange extraction process forthe recovery of metal values from dilute aqueous solutions thereof.

The inclusion of the alkylated phenol in the solvent extraction phasepursuant to the practice of this invention permits a markedly fast andsharp separation of the respective phases in effecting the extractionand stripping steps of the overall process. A further advantage ofthe'alkylated phenol over the most effective agents for this purposeknown to the art resides in the unexpected ability thereof in promotinga substantial increase of stripping efficiency, thereby resulting in acorresponding increase in the overall metal extraction efficiency.

DESCRIPTION OF THE PREFERRED EMBODIMENTS The water-immiscible organicsolvents suitable for carrying out the extraction process concernedherein include the various hydrocarbon solvents in which the chelationcollector is soluble. Other properties characterizing an acceptablesolvent are stability, low toxicity and high flash point. Such solventscan be the aliphatic, aromatic or alkyl aromatic hydrocarbons derivedfrom petroleum sources. Representative solvents are such as toluene,xylene, kerosene, various high flash naphtha cutsand the like includingmixtures thereof. A particularly preferred solvent is a kerosene cutespecially produced for extraction purposes; namely, Napoleum 470(Kerr-McGee Industries).

As indicated hereinabove, the alkylated phenols useful in the practiceof this invention are preferably used in conjunction with a metal ioncollector of the type which forms a chelate with the metal ion in theextraction recovery process. Especially effective collectors of thistype as well as the methods for the preparation thereof are disclosedand claimed in US. Ser. No. 715,879, filed Mar. 25, 1968, now US. Pat.No. 3,637,711. These collectprs are characterized in exhibiting a veryhigh loading capacity; excellent solubility in hydrocarbon solvents,particularly the aliphatic or cycloaliphatic types; essentially nilsolubility in highly acidic aqueous solutions, and outstanding chemicalstability. The preferred compounds of the foregoing type correspond tothe following structural formula:

where R and R" are hydrogen or alkyl collectively having a sum total offrom five to about 14 carbon atoms.

The 7-beta-alkenyl substituted 8-hydroxy quinolines depicted above canbe prepared by reacting an alkali metal salt of 8-hydroxy quinoline withan allylic chloride or bromide corresponding to the formula R CHCl-l(R")X wherein R and R" are as defined above. The reaction is mostconveniently carried out in the presence of an inert organic solvent.Either the non-polar solvents or polar organic solvents of lesseracidity than the 8-hydroxyquinoline are applicable. The reaction of8-hydroxy quinoline with dodecenyl chloride l-chloro-S ,5 ,7,7-tetramethyl-2-octene) yields the preferred chelation collector of theclass noted above; namely,7-[3-(5,5,7,7-tetramethyl-l-octenyl)]-8-hydroxy quinoline.

A further class of chelation collectors of the substituted oxime typeand methods for the preparation thereof can be found described inBelgian Pat. No. 688,482. Preferred collectors of this type arepurported to be the 2-hydroxy benzophenoximes which additionally cancarry alkyl substituents on either or both of the aromatic nuclei.

The alkylated phenols useful in the practice of this invention includethose alkylates of phenol wherein the alkyl moiety contains from six to12 carbon atoms. These alkylates can be readily prepared by alkylating aC C olefin or alkyl mono-chloride with phenol in the presence of aconventional Friedel-Crafts alkylation catalyst, e.g., aluminumchloride. The preferred alkylating agents for deriving the alkylatedphenols useful herein include the dimer, trimer or tetramer of propylenewhich result in the formation of hexyl-, nonyl-, and'dodecyl phenol,respectively. The nonyl phenol prepared in this manner is especiallypreferred since it is readily available as a commercial product.

It is conventional in the hydrometallurgy industry to refer to thecompositional makeup of the organic extraction medium in terms ofvolumetric proportions. This practice presumably is resorted to becausethe chelation collector as well as the surface active agent normallyused in conjunction therewith in the hydrometallurgical extraction artare liquid materials. Accordingly, the volumetric ratio of chelationcollector to the hydrocarbon solvent can acceptably range from about1:99 to 25:75, respectively. More conventionally, however, such a ratioof chelation collector to solvent ranges from 1:99 to :90, respectively.

The volumetric ratio of chelation collector to the surface active agent,usually referred to as a modifier,

broadly ranges from about 5:95 to 50:50, and more preferably from 15:85to 30:70, respectively. The organic phase comprising the metalcollector, modifier and solvent, when employed to extract a diluteaqueous solution of metal values can be used in the amount ranging from0.1 to 10 times the volume of the aqueous phase. More usually, however,the ratio of organic phase to said aqueous phase is from about 1:5 to5:1, respectively. The extraction step can be carried out as a singleoperation but more preferably is conducted in two or three stageswherein the aqueous phase flows through the extraction systemcountercurrently with respect to the organic phase. Conventionally, thepregnant or loaded organic phase is subjected to washing prior to thestripping operation. The stripping operation likewise can be conductedin one or more stages. The usual stripping solution is a strong acidsolution of such mineral acids as sulfuric acid and hydrochloric acid.It is further known that if the stripping solution contains an optimumamount of the metal values to be recovered from the loaded organicphase, stripping efficiency is optimized. Further details concerning themanner for implementing solvent extraction techniques as generallydescribed above can be found in Bulletin No. T4-B32 of the DenverEquipment Company.

In order to illustrate to those skilled in the art the best modecontemplated for carrying out the present invention, the followingworking examples are given. As indicated, these examples are givenprimarily by way of illustration and accordingly any enumeration ofdetails contained therein should not be construed as a limitation on theinvention except to the extent expressed in the appended claims. Allpercentages given are on the volumetric basis unless otherwiseindicated.

EXAMPLE I This example is illustrative of the improvement realized inthe practice of this invention in effecting the separation of a loadedorganic or solvent phase from the barren aqueous phase following anextraction operation. The barren organic phase employed in each testcontained 2.5 percent of 7-[3-(5,5,7,7- tetramethyll -octenyl]-8-hydroxyquinoline as metal ion collector which was combined with themodifier under test in the amount shown in the following Table I, withkerosene (Napoleum 470) constituting the balance.

The pregnant aqueous phase employed in each test herein was a 400 mlsolution of copper sulphate containing 2.98 grams of copper per literand having a pH of 1.5. Extraction was effected by vigorously shakingthe pregnant aqueous solution with 600 ml of the organic solution fortwo minutes. Following extraction, the coalescence rate of the aqueousphase was observed by noting the time required in attaining completeseparation. In this and subsequent examples, nonyl phenol was comparedwith iso-decanol which the industry considers to be representative ofthe most effective of the prior art modifiers.

Further details concerning the individual tests of this example,together with the results obtained are set forth in the following TableI.

the

. System A 2.5% collector; 10% nonyl phenol; 87.5% Napoleum 470 System B;93.5%

System C isodecanol 87.5%

EXAMPLE II Table 11 set forth hereinbelow. In all tests, the organicsolvent was Napoleum 470. The stripping operation consisted ofvigorously shaking the loaded organic phase with the stripping solutionfor 2 minutes in a 1 liter graduated cylinder. The results of theindividual tests are given in the following Table II.

complete separation of the phases. The coalescence data given in thefollowing Table III was obtained while conducting Test Nos. 1, 2 and 4of Example II.

TABLE III Aqueous Coalescence Rate Stripping Ml of Clear Aqueous Layer100 200 250 10 System D (Test 2, Ex. 2) 1' 48" 2' 54 3' System B (Test4, Ex. 2) 1 54" 3' 9" 3' 48" SystemF(Test 1,Ex. 2) 3'0 5'0" 6'0" Weclaim: 1. In a liquid ion exchange process for the recovery of coppervalues from a dilute aqueous solution thereof wherein said aqueoussolution is intimately contacted with a hydrocarbon solvent containingan 8-hydroxy quinoline substituted in the No. 7 position with aB-alkenyl group having from eight to 17 carbon atoms chelation collectordissolved therein to provide a loaded organic phase and wherein saidloaded organic phase is separated and thereupon intimately contactedwith an aqueous acidic stripping solution to provide a pregnant aqueousphase from whence the copper values are recovered; the improvement ofincorporating into said hydrocarbon solvent an alkylated phenol havingan alkyl moiety containing from six to 12 carbon atoms in an amountproviding a volumetric ratio of the chelation collector to the alkylatedphenol of from TABLE 11 Analysis before 2 min. contact Analysis aftercontact (g.p.l (g.p.l.)

Stripping solution Stripped Strip Cu in organic solution Test No.Organic modifier Stage organic Cu H2304 Cu Cu 1 10 vol. percentisedecanol 5Z2: 2% fig"; 3'23 i? 2 10 pe n y p e H: 53:38 8 3 7.5 vol.percent nonyl phenol g 4 5 vol. percent r10ny1pheno1.. 2g 83 1 1.82 21.10 118.10 0. 82 23. 48 5 10 vol. percent isodecanol 4 2 0.82 21.10 118.10 0.67 21 42 3 0. 67 21. 10 118.10 0.63 21.. 27 1 1.80 21.10 118.100.39 23.7!) G 7.5 vol. percent nonyl phenol 2 0. 39 21.10 118.10 0. 20.21. 3 0. 20 21.10 118.10 0.15 21. 18 1 1. 78 30. 78 148. 5 0. 51 33. 387 10 vol. percent idodecauol 2 0. 51 30. 78 148. 5 0. 37 31.08 3 0. 4130. 78 148. 5 0. 27 30. 95 8 7.5 vol. percent nonyl phenol g 2% 3854233:? 81% $8 The results of tests 1 through 4 show that the presence ofnonyl phenol substantially improves the efficiency of the strippingoperation as evidenced by the lower copper content of the strippedsolvents. The data show that there is nearly 0.4 gpl less copper in thestripped solvents containing the nonyl phenol as a modifier.

Since the amount of collector present in each test has a 55 loadingcapacity of about 1.8 1.9 g/l copper, the stripped organic solventscontaining the nonyl phenol would have an effective extraction capacityof nearly 1.7 g/l in any recycling thereof as compared to about 1.3 g/lfor the barren or stripped solvent wherein isodecanol is employed as themodifier.

EXAMPLE III This example is illustrative of the improvement realized inthe practice of this invention in effecting the separation of a barrenorganic phase from a loaded about 595m 50:50, respectively.

2. The improvement in accordance with claim 1 wherein said alkylatedphenol is hexyl phenol, nonyl phenol, dodecyl phenol or mixturesthereof.

3. The improvement in accordance with claim 2 wherein said alkylatedphenol is nonyl phenol.

4. The improvement in accordance with claim 3 wherein said chelationcollector is 7-[3-(5,5,7,7- tetramethyll -octenyl l-8-hydroxyquinoline.

5. The improvement in accordance with claim 4 wherein the chelationcollector and the hydrocarbon solvent are present in a volumetric ratioof from about 1:99 to 25:75, respectively.

6. The improvement in accordance with claim 5 wherein said chelationcollector and nonyl phenol are present in a volumetric ratio of from15:85 to 30:70, respectively.

7. The improvement in accordance with claim 6 wherein the chelationcollector and the hydrocarbon solvent are present in a volumetric ratioof from about 1:99 to 10:90, respectively.

2. The improvement in accordance with claim 1 wherein said alkylatedphenol is hexyl phenol, nonyl phenol, dodecyl phenol or mixturesthereof.
 3. The improvement in accordance with claim 2 wherein saidalkylated phenol is nonyl phenol.
 4. The improvement in accordance withclaim 3 wherein said chelation collector is7-(3-(5,5,7,7-tetramethyl-1-octenyl))-8-hydroxyquinoline.
 5. Theimprovement in accordance with claim 4 wherein the chelation collectorand the hydrocarbon solvent are present in a volumetric ratio of fromabout 1:99 to 25:75, respectively.
 6. The improvement in accordance withclaim 5 wherein said chelation collector and nonyl phenol are present ina volumetric ratio of from 15:85 to 30:70, respectively.
 7. Theimprovement in accordance with claim 6 wherein the chelation collectorand the hydrocarbon solvent are present in a volumetric ratio of fromabout 1:99 to 10:90, respectively.